TRAINING IN USE OF DMX ELECTRONICS

有三种类型的重新编码：核糖体移码， 终止密码子通读，并绕过内部信使核糖核酸区域。重新编码 说明书可能包括在信使核糖核酸中的RNA结构。这些 结构可以动态地改变mna通过 核糖体，可以直接与核糖体结合，并可以结合 蛋白质或其他辅助因子，并使它们到位，以指导 记录事件。在通用代码中，UGA密码子发出信号 蛋白质合成的终止。此事件可以在 三种途径，包括硒半胱氨酸的共翻译插入 这个三联体(通读的特例)。对于硒半胱氨酸 在真核生物中，在终止密码子处插入有四个要求： (1)合成硒半胱氨酸所必需的两种酶 氨基酸；(2)一种特殊的tRNA；(3)RNA茎环结构，称为 糖半胱氨酸插入元件(SECIS)是3‘-非编码区所必需的 和；(4)一种可以作为mRNAs同源的蛋白质 原核生物SELB蛋白(SBP)被认为与SECIS和SECIS结合 为插入硒半胱氨酸的核糖体编程。一种核磁共振结构 对这种结构的研究将有助于理解元素是如何 在3‘-非编码区中，特定的信使核糖体“通知”翻译 与所有UGA密码子相同的mRNA，但末端除外 密码子，应指定硒半胱氨酸插入。两种型号的 SECIS二级结构可用。这两款车型都确定了两种 茎被内部环分开，除了顶端环。 系统发生学鉴定环II中有三个连续的腺苷，而一个 在“核心”区域运行或4个碱基对，这对 SECIS的功能。STEM II的基址配对寄存器不同之处在于 这两个模型由一个核苷酸包括两个串联的G-AS组成，它们是 建议使用N6-A到N3-G和N7-A到N2-G组成 H-键，为U-U的受限几何构型提供了空间 纵队两侧的基地。这些有趣的螺旋线 安排是特别认可环境地政总署的理想地点 真核糖半胱氨酸插入同源(SBP)蛋白。A43 已生产出与stemII/loopII相对应的核苷酸RNA 利用径流T7转录结合双链进行核磁共振研究 核酶裂解产生同源的RNA。西米诺的共鸣 该核糖核酸的1D~1H谱在化学位移范围内 预期为G-A碱基对。此属性强烈建议使用模型B 与该SECIS RNA的stemII/loopII区更加一致。 已经纯化了一个较小的RNA，它对应于具有 UUCG四环取代loopII，简化词干分配 共鸣。该RNA间接证实了碱基配对 通过强制使用此词干，注册为与模型B一致 使用四环结的排列，并观察到近 完全相同的亚米诺光谱。同核2D-1H数据表明 与模式B相同的碱基配对排列，但受到以下限制 1H谱中的简并现象。这些RNA的同位素富集化 将是更完整的任务所必需的 高分辨率结构的确定。其中包括完整的 ~(15)N和~(13)C中RNA的随机同位素浓缩和选择性 特定核苷酸的浓缩。

There are three classes of recoding: ribosomal frameshifting, stop-codon readthrough, and bypass of internal mRNA region. Recoding instructions may include an RNA structure within the mRNA. These structures can kinetically alter the mRNA passage through the ribosome, can interface with the ribosome directly, and can bind proteins or other co-factors and bring them into place to direct the recoding event. Within the universal code, the UGA codon signals the termination of protein synthesis. This event can be circumvented in three ways, including co-translational insertion of selenocysteine at this triplet (a special case of readthrough). For selenocysteine insertion at stop codons in eukaryotes, there are four requirements: (1) two enzymes essential for the synthesis of the selenocysteine amino acid; (2) a special tRNA; (3) an RNA stem-loop structure, termed the selnocysteine insertion element (SECIS), is required in the 3'-UTR of the mRNAs and; (4) a protein which may act as the homologue to the prokaryotic SelB protein (SBP) is thought to bind the SECIS and program the ribosome for selenocysteine insertion. An NMR structural investigation of this structure will help to understand how an element in the 3'-UTR of a specific mRNA "informs" ribosomes translating that same mRNA that all UGA codons, with the exception of the terminal codon, should specify selenocysteine insertion. Two models of the SECIS secondary structure are available. Both models identify two stems separated by an internal loop, in addition to an apical loop. Phylogeny identifies three consecutive adenosines in loop II, and a run or 4 base-pairs in the "core" region that are essential for the function of SECIS. The base pairing register of stem II differs in the two models by one nucleotide including two tandem G-As which are proposed to be formed using N6-A to the N3-G, and a N7-A to N2-G H-bonds, allowing room for the restricted geometry of the U-U basepairs that flank the tandem. These intriguing helical arrangements are ideal sites for specific recognition of the SelB homologue (SBP) protein for eukaryotic selnocysteine insertion. A43 nucleotide RNA corresponding to stemII/loopII has been produced for NMR studies using runoff T7 transcription in conjunction with double ribozyme cleavage to produce homogeneous RNAs. Simino resonances in the 1D 1H spectra of this RNA lie within the chemical shift range expected for G-A base pairs. This attribute strongly suggests model B to be more consistent with the stemII/loopII region of this SECIS RNA. A smaller RNA has been purified, which corresponds to stemII with a UUCG tetraloop replacing loopII, to simplify the assignment of stem resonances. This RNA has indirectly confirmed the base pairing register to be consistent with model B, by forcing this stem arrangement using the tetra-loop junction, and observing a nearly identical imino spectrum. Homonuclear 2D 1H data have suggested the same base-pairing arrangement of model B, but have been limited by degeneracies in the 1H spectra. Isotopic enrichment of these RNAs will be essential for more complete assignments required for the determination of a high resolution structure. These include complete random isotopic enrichment of RNAs in both 15N and 13C, and selective enrichment of specific nucleotides.